所謂基地使用權人之優先購買權，係指權利人於所有人將其基地或房屋出賣與第三人時，有權以意思表示，在同樣條件下優先於第三人承買之權利。土地法第一百零四條及民法第四百二十六條之二均有規定。基地之使用權人在什麼情況下，得主張優先購買權？本文將以基地租賃為例，探討基地承租人在土地所有人出賣土地時，其行使優先購買權之要件，及其於實務上所發生之相關爭議問題。

Right of First Refusal refers to the entitlement of priority to the person of preemptive rights, under the same condition, to purchase the land in a transaction of land(station) or building amongst three persons. Article 104 of Land Act and Article 426-2 of Civil Code both rule that, in the wake of the sale of property or land(station) by the owner, superficies holders, lien holders, and tenants are all entitled to, under same condition, the preemptive right. This article will focus on the discussion of the conditions applied in the context of Right of Preemption and its related issues, as well as the analysis of related theories and in practice.